CSPAN download is two videos combined together

[wesnm]

Checklist

• I'm reporting a broken site support
• I've verified that I'm running youtube-dl version 2020.09.20
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar issues including closed ones

Verbose log

[morganw@volatile:~$]: youtube-dl -v "https://www.c-span.org/video/?476429-1/south-carolina-us-senat
e-debate"                                                               
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-v', 'https://www.c-span.org/video/?476429-1/south-carolina-us-senate-debate']
[debug] Encodings: locale UTF-8, fs utf-8, out utf-8, pref UTF-8
[debug] youtube-dl version 2020.09.20
[debug] Python version 3.8.6 (CPython) - FreeBSD-13.0-CURRENT-amd64-64bit-ELF
[debug] exe versions: ffmpeg 4.3.1, ffprobe 4.3.1, rtmpdump 2.4
[debug] Proxy map: {}
[CSpan] 476429: Downloading webpage
[CSpan] 553942: Downloading JSON metadata
[CSpan] 553942: Downloading XML
[debug] Default format spec: bestvideo+bestaudio/best
[debug] Invoking downloader on 'https://media.c-spanvideo.org/dynamic/2020/10/03/20201003192953001_hd/20201003192953001_hd.MP4-M20.mp4?Policy=eyJTdGF0ZW1lbnQiOlt7IlJlc291cmNlIjoiaHR0cHM6Ly9tZWRpYS5jLXNwYW52aWRlby5vcmcvZHluYW1pYy8yMDIwLzEwLzAzLzIwMjAxMDAzMTkyOTUzMDAxX2hkLzIwMjAxMDAzMTkyOTUzMDAxX2hkLk1QNC1NMjAubXA0IiwiQ29uZGl0aW9uIjp7IkRhdGVMZXNzVGhhbiI6eyJBV1M6RXBvY2hUaW1lIjoxNjAxNzg5ODc0fSwiSVBBZGRyZXNzIjp7IkFXUzpTb3VyY2VJcCI6IjczLjU5LjEyOS43MCJ9fX1dfQ__&Signature=Dr5Vf9LXl6Tc~gtXwoDd-7OkzI-2nAWwJmZWdK8HIhs5YtqwfYBcz7eMtQkuHv4GFYo53lfL0zXD0TVaLChqXBa2L~4z1lmusItVAbpcbBZ9ZD48nwU0MFY~z~-SWHZTwPJLvTj-RgbdjoZCnFAvVVfWyZXh5XAVv8KdgeQBWfw_&Key-Pair-Id=APKAIHKVWBEAXX562G7Q'
[download] Destination: South Carolina U.S. Senate Debate-553942.mp4
[download] 100% of 221.02MiB in 00:37

Description

The downloaded video is an hour long as expected, but the first 30 minutes are not from the correct stream. The actual video starts about halfway through.

[october262]

try the command like this - youtube-dl https://www.c-span.org/video/?476429-1/south-carolina-us-senate-debate -f mp4
you will get 3 files, the first & third are video and the 2nd is i'm guessing a dummy file